A turn-on fluorescent nanoprobe for lead(II) based on the aggregation of weakly associated gold(I)-glutathione nanoparticles

The authors describe a method for ethanol induced formation of a fluorescent nanoprobe for sensitive fluorometric “turn-on” detection of Pb 2+ based on aggregation-induced emission (AIE) of the Au(I)-glutathione (GSH) complex. On addition of Pb 2+ , their strong interaction with GSH causes the Au(I)-SG complexes to come in close proximity, and this results in a turn-on fluorescence with a strong emission peaking at 595 nm. The findings were utilized to design a method for quantitation of Pb 2+ . Interestingly, sensitivity is largely enhanced in the presence of ethanol due to the formation of dense Au(I)-SG nanoparticles. The fraction of ethanol is optimized. Response to Pb 2+ occurs within a few seconds. The assay covers the 2.0 to 350 μM Pb(II) concentration range, has a 0.1 μM limit of detection, and has a satisfactory selectivity over other environmental metal ions. Graphical abstract Au(I)-SG complexes can form dense Au(I)-SG nanoparticles induced by ethanol. The solvent-stimulated Au(I)-SG nanoparticles show high sensitivity towards Pb 2+ because they facilitate aurophilic interactions.